Such accessories are well known and are described in numerous documents. One, described in a patent application EP 344,859, is constituted of several rigid pieces interconnected by joints, of anti-projection means and of means conveying air-milk-steam complexes. This accessory is cumbersome, difficult to emplace and remove and does not permit obtaining the maximum emulsion necessary for the obtention of a good "cappuccino". Moreover, the construction of such an accessory is not well adapted to mass production in which the pieces must be simple, and small in number, to permit automatic and economical assembly.
The object of the invention is to overcome the above drawbacks by providing a simple and economical accessory which will be easy to mount on the steam output pipe of an espresso coffee machine.